docs: def retreive_sigma_mu_data(self):
          """
          For the general form of the GMPE this retrieves the sigma mu
          values from the hdf5 file using the "general" model, i.e. sigma mu
          factors that are independent of the choice of region or depth
          """
          fle = h5py.File(os.path.join(BASE_PATH,
                                       "KothaEtAl2019_SigmaMu_Fixed.hdf5"), "r")
          self.mags = fle["M"][:]
          self.dists = fle["R"][:]
          self.periods = fle["T"][:]
          self.pga = fle["PGA"][:]
          self.pgv = fle["PGV"][:]
          self.s_a = fle["SA"][:]
          fle.close()